Thanks to Alpine Bikes in Glentress we have been spending some time on the latest suspension platform from Yeti, the SB-66.
Dubbed the Super Bike (SB) by Yeti under its secretive construction and testing process, on first glance the bike looks to be like any other linkage driven bike in the array of platforms currently available. However, under closer inspection you may spy a suspicious looking arrangement sitting just above the bottom bracket. This is the heart of the SB’s ground breaking new suspension system, snappily named the ‘switch’.
In the pursuit of perfect suspension, many designs have come and gone, and to better understand why, we must first look at the geeky subject of axle paths, the direction the rear axle moves when hitting a square edged object. If you imagine a single pivot bike, with the main pivot mounted near the bottom bracket, when it strikes an object the axle moves upwards and slightly forwards as the swing arm cantilevers at the bottom bracket. Although this system works to good effect in many current bikes it is inherently floored in one principal way, as the axle is able to move in a slightly forward direction any forces through the chain will tend to want to pull the axel forward (and thus up as it can only move in an arc). So when you are out of the saddle and trying to power up a steep climb, all that force driven through the chain on each pedal revolution and body movement causes the back axel to be pulled up and forward, resulting in regular oscillations known well as ‘pedal bob’. Single pivot bikes have come a long way since the early pogo days, and modern shock technology has done a lot to filter out the unruly behaviour, relying on platform damping stiffening up the initial stoke phase. Clever as these shocks are they are still covering up for an inherent flaw in the single pivot design. We have also seen many new designs hit the market, from the tried and tested FSR linkage, Giants Maestro and various workings on the VPP and ABP designs. These systems are all effective but still suffer in varying degrees finding that elusive compromise between active suspension and pedalling efficiency. So why not make the axle path travel up and rearwards, this would offer zero pedal induced feedback and help to release energy from a direct hit? The problem lies in chain growth, if you have a lot of suspension travel and a rearward axel path, as the axel moves back it increases the physical length between the bottom bracket and the hub and causes increased tension on the chain which will eventually resist the travel. So it would seem that the perfect suspension platform, the holy grail if you like, would have a rearward direction but be un-influenced by chain growth.
This is where Yeti’s new Switch Technology confidently enters the fray! The main pivot bearing is mounted on an eccentric rotating cylinder, cleverly mounted off centre. This means that as the pivot rotates through its travel, the off centre mounting allows the axel path to change direction – the switch! Initially the axel path of the SB66 is rearward and upward, and then as the travel passes into the mid and final stroke the path switches to forwards minimising chain growth. So under pedalling the all important first third of the stroke is rearward and thus suffers no pedal induced shortening, and no bob, as the hits get bigger the stroke can shift into a more forward direction minimising inhibition caused by chain growth as it delivers 150mm of plush travel. This simple idea may well be the biggest advance in suspension technology since we stopped putting elastomers in our forks.
So how does all this technology reflect in the ride of the SB66? From the first few pedal strokes on the bike the intentions of the bike become immediately crystal clear, pure speed! The low and long bike feels planted and taught and there is instant power pickup as you hit the pedals, there is no lag from the suspension when you power down, the bike simply surges forward in a way that no other current 150mm travel bike can come close to. Looking at the back end as you pedal there is minimal bob from the swing-arm, it just quietly gets on with the business of bump absorption. The switch system comes into its own on climbs, where the SB drives up the hill with intent and lightness that defies its long travel roots. I would say it is a more accomplished climber than most of the 120mm travel bikes currently on the market and you can really feel the switch system dialling out power loss. Short technical climbs and long drawn out slogs are deftly dispatched and the bike always feels poised and tracks well when the going gets steep. The long wheelbase keeps the front wheel planted and there is minimal wandering.
When it comes to descending over rough terrain and the bike starts working through its travel, you will be rewarded with control and poise that allows you to carry insane speeds. A lot of 150mm travel bikes are either too plush, like over sprung sofas that remove you from the trail isolating you from the contours and removing important feedback, or at the other end of the spectrum bikes touted as efficient peddlers sacrifice ride quality through being too firm and unsophisticated, getting out of shape and unruly in rough ground. The Yeti manages to find that elusive middle ground, the suspension actively dealing with impacts while maintaining precise feedback with the terrain. Small bump sensitivity is good, it is not super plush in the mid stroke but that is not what this bike is all about! This firmness in the mid stroke allows immense pop and speed out of berms and lets the bike find massive traction in the turns, this bike rails everything and will pop you out of corners at warp speed if you have the minerals to hang on. If you like your bikes super plush, you would be better looking to the 575, the SB66 is a race machine wrapped up in an All Mountain package! That is not to say that it feels uncomfortable, harsh or overly stiff, Yeti have built a bike that feels alive, confident, poised and accurate, this is an aggressive bike that can be ridden all day and wills you to go faster and faster.
We tested the bike weighing in at 28.6lbs with an excellent XT group set, Fox 150 Kashima 32 Fork and high end Thomson and Easton finishing kit. If you are more into gravity riding the SB can take a 36 fork up front giving a head angle of 66.3 degrees (67 degrees with a 150mm 32) and will handle any amount of abuse that could be dished out on any track in the UK. If you are in the market for a new 150mm travel bike, or even a superb trail bike and like your riding on the fast and fun side, you have to demo this bike!There can be no doubting the SB66’s outright speed and handling, there is simply no equal in the current crop of big hitting All Mountain bikes. The bike hits that magically quality of feeling composed and neutral in the corners without losing that vital liveliness and engaging ride that proves elusive for many manufacturers. Only time will tell how well the switch holds up to UK winters, and if it will prove to be the Achilles heel in perhaps the most groundbreaking and innovative suspension platform yet. So far long term tests have been very promising and if the switch does prove to be as durable as Yeti claim, the SB66 could well be the finest ‘do it all’ platform currently available.
This bike is nothing short of a revelation, perhaps this marks a new breed of machines born out of the growing popularity of the new Enduro race format, I can think of no other bike that would be faster on mighty events like the Megavalanche, where riders need to combine blistering downhill speed with lung sapping climbing. But the SB is so much more than that, this machine would be equally happy racing in a 100km XC marathon and in the same spec could smash out some fast times on the local downhill track. All credit to the designers at Yeti, the sofa is dead! Long live the SB…